Fourth COVID-19 vaccine: efficacy, duration and who will receive it

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In Spain, 40.6 million people have received the full schedule of vaccination against COVID-19 (85.7% of the total population, counting those that remain outside the target population), 55.4% of those under 12 years of age have at least one dose and 54.5% of the population has received the booster or booster dose.

“The data is generally positive”with a “truly exemplary” acceptance in most cases (a little slower in young people and those under 12 years of age, for various reasons) and “massive” in older groups: “the high coverage in higher doses souvenirs are very remarkable”, analyzes Jaime Jesús Pérez, member of the Spanish Association of Vaccinology (AEV).

Now, the next step in Spain is the administration of a second booster dose, already implemented in several surrounding countries. This is still under evaluation by the authorities and has generated debate among experts about whether it is necessary in the entire population and when it should be injected.

This is what is known about the fourth COVID-19 vaccine, which is still surrounded by some uncertainties:

Why is it going to be administered?

Covid-19 vaccination in SpainCovid-19 vaccination in Spain

The reason that the health authorities of the European Union allude to for recommending the fourth vaccine now is the “new wave” of coronavirus that Europe is experiencing —and, with it, Spain—reflected in an increase in cases and an “upward trend” in admissions to hospitals and intensive care units.

In it are playing a prominent role the omicron sublineages BA.4 and BA.5which are changing the epidemiological landscape with new, more numerous, and sometimes more intense symptoms, so that COVID-19 disease seems to move away from the pattern of a cold and toward that of the flu.

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Also, with the second booster dose, the aim would be to “raise the protection again” immune system against the coronavirus, especially of the most vulnerable population, to avoid hospital admissions and serious illness.

“The most important vaccines administered are primary vaccinations, but once you have achieved that, you are no longer satisfied. Now what you need is logically to the last admission you can avoid and to the last life you can save: that’s what it’s all about doing with those booster doses.”explains Jaime Jesús Pérez, in an interview with Business Insider Spain.

2 vaccine type options: the current ones or adapted to the new variants

A test tube labeled Test Positive for the omicron variant of COVID-19A test tube labeled Test Positive for the omicron variant of COVID-19

One of the doubts that the fourth dose leaves against covid is the type of vaccine that should be used, which presents 2 possible scenarios: use currently existing vaccinesbased on the original strain of the coronavirus, o wait until the doses adapted to the new variants are developed and approved.

EU health agencies They have recommended this Monday 11 to take advantage of the current ones and “not wait” for the new ones (of which it is expected that they could be authorized in September), in view of the current epidemiological situation. Some recommendations that “are not easy to understand,” according to Pérez.

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Lorenzo Armenteros, spokesman for the Spanish Society of General and Family Physicians (SEMG), also disagrees with the authorities:

A third or fourth dose with existing vaccineswhich are based on the Wuhan strain, the one from the beginning of 2020, Has no sense now, because they are going to give very little protection for the new variants” and it could even be harmful in some cases, he defends in statements to Business Insider Spain.

yes i would have one revaccination with vaccines appropriate to the variants that are circulating at that moment,” he contradicts.

For now, it seems that they would be messenger RNA vaccines.

When will the fourth coronavirus vaccine be administered?

Red Cross worker wearing a mask during the Covid-19 pandemicRed Cross worker wearing a mask during the Covid-19 pandemic

Since January, immunosuppressed people are already receiving the second booster dose in Spain, but it is not yet known when the rest of the population will receive it.

The EMA (European Medicines Agency, for its acronym in English) and the ECDC (European Center for Disease Control and Prevention) have suggested that it be “immediately”, and pointed out that could be administered at least 4 months after the previousfocusing on people who received a previous booster more than 6 months ago.

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From the Public Health Commission it is pointed out that “it is highly probable that, to prevent serious illness, it is convenient to administer a booster dose in the fall”although finally it is proposed to establish “the most appropriate moment according to the epidemiological situation” and continue to assess it “regularly”.

For his part, Armenteros is committed to inoculating the fourth vaccine “as soon as they are available” the doses adapted to the variants highest circulation at the time.

However, Jaime Jesús Pérez defends leave them for the autumn vaccination, which “will be key”because that is when “the Christmas wave, November-December, which have always been the most powerful waves” is expected.

Regarding the time interval between this dose and the previous one, he also speaks of “minimum 4 months, more recommended 6 months”.

Who would receive the second booster dose, and how would it be administered?

COVID vaccineCOVID vaccine

The Public Health Commission raises in its proposal June that “it will be necessary to administer a second booster dose in the most vulnerable population, especially in nursing home inmates and adults aged 80 and over”.

From there, according to Health, it would go down by age groups, from highest to lowest priority, as has been done with previous injections against this virus. The debate, opened by some statements by Minister Carolina Dariasarises around if the fourth COVID-19 vaccine will also be “for the entire population”.

Jaime Jesús Pérez plays down what he considers to be a specific “error” by the minister and proposes limiting it to vulnerable people, since most people continue to have the disease “without much significance”.

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“Honestly, I believe that for the entire population a booster dose recommendation —unless something happened that we haven’t seen at the time— wouldn’t seem very suitable”says this doctor specializing in preventive medicine.

The exception: the emergence of “a new variant that has a full escape” to hybrid immunity and can cause serious illness, “but it is a very unlikely scenario,” he clarifies.

The EMA and the ECDC recommend not lower than those over 60 years of age (and people at risk of any age) and affirm that “for the moment, there is no clear evidence” to support the administration of a second booster for the rest of the citizenry.

Armenteros disagrees: “Vaccines have to start in the same way for the most fragile people as soon as possible and they have to be revaccinations of the entire population”always with doses containing “the variants that are most circulating at that time”.

Efficacy, duration and available scientific evidence

Moderna booster vaccine against COVID-19Moderna booster vaccine against COVID-19

Given the lack of data in Spain on the efficacy of the fourth coronavirus vaccine, these come from other countries, mostly from Israel.

“The observed results of effectiveness of the 4th dose of mRNA vaccine in Israel during the beginning of the omicron variant wave show that the risk of serious infection and/or death from COVID-19 decreases up to 10 weeks later of receiving a fourth dose compared to those receiving only the third dose, pick up Health.

However, the ministry acknowledges that the duration of this protection is not yet known.

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In the Spanish context, different from that of Israel (Israeli rates of infection by omicron were then among the highest in the world), “an expected decrease in effectiveness is observed over time, especially in older people,” he adds. .

“What vaccines have taught us so far is that against serious illness in admissions and hospitalizations it lasts longer [la protección]: can last approximately 6 months, depending on the age group. Also what we have seen is that with omicron the duration is shorterespecially against infection, but also against serious illness”, shares Jaime Jesús Pérez.

As for the bivariate vaccines (based on parent strain and omicron variant), “what is expected is that they achieve greater protection” and that this is “longer lasting over time”foresees the member of the Spanish Association of Vaccinology.

It won’t be the last

Older people with a mask due to COVID-19Older people with a mask due to COVID-19

In any case, it does not seem that this fourth vaccine will be the last to be administered in Spain, at least to certain population groups.

This expected somewhat longer-lasting protection has a limit: “We are probably talking about administering an annual booster dose to certain people in risk groups.; we don’t think about anything else”, she clarifies.

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It is “a contemplable hypothesis”, a “quite possible scenario”: if the virus becomes seasonal and epidemic waves arise in autumn-winter, it will be necessary to have vaccines adapted to new variants and that provide more protection, the expert believes.

However, “it is very important to highlight that with the vaccines the most important thing has been achieved.” “They have served a lot, and have prevented many deaths and they continue to avoid many hospital admissions. What happens is that the drop in that vaccine protection can drop you from 90% to 80% to 70%, and that memory dose can raise your protection back to 90%”Explain.

“That is the key: to ensure that a certain population that may be more sensitive and vulnerable is more protected, so that in this way they do not have hospital admissions,” he concludes.

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